Pressure gauge



June 12, 1945. L. DE WAN PRESSURE GAUGE Filed' June 16 1943 2Sheets-Sheet 1 INVEM'OR Zeowflewan/ Ma omv'mr June 12, 1945. DEWAN2,373,201

PRESSURE GAUGE Filed June 16, 1943 I Sheets-Sheet- 2 INVENTORLeonflewanv TORNE Y Patented June 12,1945

UNITED STATES PATENT OFFICE.

PRESSURE GAUGE Leon Dewan, Arverne, N. Y., assignor of one-half toPercival W. Andrews, New York, N. Y.

Application June 16, 1943, Serial -No. 490.980

' 6 Claims. (01. 13414) This invention relates generally to improvementsin pressure-gauges particularly to the Bourdon type.

An object is to reduce the effect of vibration on such gaugeswhether itcomes from an external source or from sudden irregularities in thepressure of the metered fluid.

Another object is to eliminate wear on the moving parts of the gauge.

According to the present invention, the pressure responsive element suchas a Bourdon tube' has one of its extremities connected to a pivotedgear segment by linkage, one end of the linkage extending to one side ofthe pivot and being fastened tothe periphery of the gear segment, theother end of the linkage which extends on the other side of the pivotbeing connected directly to the extremity of the tube and receiving themotion of the tube. The motion of the tube is thus transmitted through areversed path whereby unusual and extraordinary flexure is applied tothe linkage against any resistance, such as inertia of the gear segmentwhen the applied motion is of high speed. The linkage has a certainamount of flexibility, depending upon the inertia of the gear segment,but at the same time it is'sufliciently-rigid so that pressure changesoccurring at normal speed are accurately and normally transmitted asthough the flexible linkage and gear segment were of one piece. However,with increase of speed in the motion, such as when the Bourdon tubevibrates, the linkage flexes in proportion to the parts being brokenaway.

velocity of the motion against the inertia of the gear segment.

. The linkage is bentto contact the surface of the segment and toproduce a certain amount of frictional resistance to independent motionbetween the linkage and segment due to linkage flexure. This helps toabsorb the high speed motion and reduce the tendency of the gearsegmentto oscillate. There is also a reaction on the tube itself in thisarrangement whereby the original vibration thereof is reduced inamplitude. I

. Where the gauge is used on a moving vehicle or under other conditionsof external vibration, the device may incorporate at the same time themechanism described in my'copending application Serial No. 450,153,filed July 8, 1942, whereby the gear segment or other member is made toturn in an opposite direction to that of the Bourdon tube and be of suchmass as to stabilize the moving parts of the gauge under the influenceof rotative acceleration.

Fig. 2 is a top plan view of the mechanism of Fig. 1 with the casingremoved, and parts being broken away. 1

Fig. 3 is a front elevational view of a modified form of moving partsfor a Bourdon gauge, .parts being broken away.

Fig. 4 is a top plan view of the mechanism of Fig. 3, with parts beingbroken away.

Fig. 5 is a front elevational view of another modified form of movingparts for a Bourdon gauge, parts being broken away.

Fig. 6 isa top plan view of the mechanism of Fig. 5, with the scale andbase plate added.

Referring to Figs. 1 and .2 of the drawings,

the gauge comprises an outer casing I having a.

scale 8 at the front. A tube 9 formed preferably of copper and circularor oval in cross section is mounted inside of the casing. This tube hasone of its extremities l0 extending through the casing wall. Thisextremity I0 is connected to a reservoir or other enclosed space (notshown) containing the fluid v.to be measured by the gauge.

The other extremity ll of the tube is connected to a needle l2 whichtraverses the scale 8. The present invention is concerned with theconnection between the extremity II and the needle l2. In the form ofthe invention shown in Figs. 1 and 2, a frame comprising rear and frontplates l3 and M, respectively, connected by posts I5, is fastened to theinner surface of the base of the casing in any suitable manner. A shaft[6 is rotatably mounted in the plates l3 and I4 and carries the needleI! at its front end for movement over the face of the scale 8. A pinionor spur gear I! is fastened to shaft l6 centrally of the frame. A.gearsegment I8 is pivotally mounted in the frame by means of a pivot pin l9and arranged so that it is in line with the pinion l1 and so that theteeth 20 on 5 its outer periphery are in mesh with the teeth of thepinion. A hair spring 2| with one of its I ends fastened to one of theposts l5 and its other end to the shaft l6 tends to rotate said shaft ina direction to keep the teeth of pinion l1 pressing against the teeth ofthe gear segment to prevent back lash. Arcuate weighted members 22 maybe carried by the gear: segbowed portions 28 providing an openingthrough which the pivot pin l9 extends and which opening 29 communicateswith the slot 21. The extremity ll of the tube 9 is connected to thislink 23 by a rigid link member 30, one end of which is fastened to theextremity II and the otherend of which carries a pin 3| which extendsinto and through the slot 21 in the link 23. The link member 23 isformed of resilient metal such as beryllium copper or steel and is bentas indicated at 32 so as to press the remainder of the link body againstthe surface of the gear segment and thus create frictional resistanceagainst displacement of the link relative to the gear segment.

Ordinarily when the pressure within the tube increases, the tube changesits formor shape, that is, its curvature diminishes, and the. freeextremity ll thereof moves away from the fixed extremity thereby movingthe needle or pointer l2 over the scale 8. Movement of extremity II isimparted to the pointer by means of the link members 30 and 23, gearsegment I 8 and pinion I 7 as though these parts constituted a singlepiece pivoted on the pivot pin l9, and a faithful reading follows.However should thetube 9 vibrate either from sudden pressure fluctuationor external forces, the link member 23 flexes against the resistance ofthe inertia of the gear segment iii in proportion to the velocity of themotion, the efiect of the inertia resistance on the flexure of linkmember 23 being multiplied by the arrangement because of the reversedtransmission path from pivot pin 3| to pivot pin 19. The link member 23then absorbs the vibration by moving relative to the gear segment asshown by the dotted line in Fig. 1.

The frictional engagement between the link member 23 and the gearsegment' l8 reduces independent oscillation of the gear segment as thepointer or indicator takes a position approximately half way between thelimits of the vibra- Intermeings of the moving parts. The inertia of thegear segment is then made to cause a sufficient yielding of the linkmember 23 at a chosen velocity of motion. Preferably the mass around thepivot point l9 should be balanced relative thereto.

If the required inertia was produced by mounting an inertia disk on theshaft IS, the same result would be secured but the strain of vibrationabsorption would pass through the gear teeth with consequent wear on thesame. In fact it is advantageous. to have the gear segment be ofsufiicient mass and the pinion II with the pointer be as light aspossible to keep the teeth in light but steady contact at all times,while the vibration isabsorbed before reaching this part.

Where the-gauge is employed on moving vehicles or under other conditionsof external vibration likely to impair the accuracy or steadiness of thereading, the form of the invention with slot44 positioned adjacent theextremity tional motion and therefore registers the mean resistancebetween the gear segment and link.

member 23 should be initially adjusted, taking into consideration theinherent rigidity of the link member23, so as not to leave thelinkmember 23 in any way. displaced from normal position relative to thegear segment when the 3 vibration has stopped. A heavy oil or grease maybe applied to the parts and where metal to metal frictional contact isto be avoided a renewable piece of fibre, leather or. rubber may beinserted between link member 23 and the gear segment at thepressurecontact point.

The gear segment need not be heavy in view of the flexibility of thelink 23. It is only re- 7 q l jd that the member 23 be rigid enoughtoallow faithful. indicator following of the normal speed tube motionagainst friction of the bearll of tube 9 is connected to said extremityby a link 45 having a'pin 46 extending into said slot 44 and ridingtherein. The opposite end of link 4| is connected to the gear segment 18by a link 41 having a pin 48 riding in its slot 43. This link 47 ispivotally connected to a link 49 having one of itsends fastened to thegear segment at 50 at the edge of said segment opposite its toothedperiphery. This'link 49 is formed with an opening 5| through which thegear segment pivot pin l9 passes.

The main difference between the two forms is that the gear segments turnin opposite directions. In the form of Figs. 3' and 4, weighted members52 on the gear segment are arranged to balance the masses moving aroundpivot pin l9 as a center. At'the same time, a weighted member 53 isarranged to balance as much as possible the masses moving around pivotpin 42 as a center. This includes that of the free portion of the tube9. Under the influence of a rotative acceleration vibration conditions,the

mass of the gear segment is such as to oppose with approximately equalforce the inertia of the masses moving around pivot pin 42 and alsoaround the shaft IS with the result of stabilization as described in mycopending application aforesaid. Whatever residue of motion is left dueto imperfect balancing of the system is easily absorbed by thefriction-already provided for between the gear segment and the linkage.

In the form shown in Figs. 5 and 6, the tube 9 is connected to thepointer 60 by mechanism including an elongated link member 6| secured atone of its ends to the toothed periphery of the gear segment 32 asindicated at 63. The

other end of the link 6| is connected to a link.

64 which is fastened to the extremity. H of the tube. The link 6| isbent as indicated at 65 to provide frictional resistance between saidlink GI and the gear segment. i

I claim:

actuating element, an indicator, a linkage connection between saidelement and indicator, one of the links of said connection being of suchresiliency as to yield to the vibrational component of the motion of theactuating element and being of sufiicient rigidity to transmit thenormal speed motion of said element faithfully to the indicator, saidlink having frictional engagement with an associated link whereby selfoscillation of the linkage is absorbed 2. In a pressure gauge, apressure responsive actuating element, an indicating member, a linkageconnection between the actuating element and the indicating member, asemi-resilient link in ment intermediate of its length with anassociated link whereby resilient motion of said link due to high speedmotion of the actuating element is subjected to damping absorption.

3. In a pressure gauge, a pressure responsive actuating element, anindicating member, a linkage connection between the actuating elementand the indicating member including a gear segment, one of the links ofsaid connection being resilient and being fastened to the gear segmentand frictionallyengaging the segment beyond its point of attachment fordampening the resilient motion of said link.

4. In a pressure gauge. a pressure responsive actuating element, anindicator, a linkage connection between the actuating element andindicator including a pivoted member one of the links of said connectionbeing resilientand being fa itened at one end thereof to said pivotedmember, the

path from the point of applied motion on said latter link to thefastening point proceeding in a different direction than that of thepath from the fastening point to the pivot of said pivoted member, saidresilient link frictionally engaging said pivoted member whereby selfoscillation of the auge mechanism is absorbed.

5. In a pressure gauge, a pressure responsive actuating element, anindicator, a linkage connection be ween the actuating element and theindicator including a pivoted gear segment, one of the links of saidconnection being resilient and being fastened to the gear segment atoneside of the pivot at one of its ends and motion being imparted to saidlink by said actuating element at the other side of said pivot, saidresilient link frictionally engaging said pivoted member whereby selfoscillation of the gauge mechanism is absorbed.

6. In a pressure gauge, a Bourdon tube, a rigid link member having oneerid fastened to said tube, an elongated resilient link member and apivoted segment lever, a slot and stud connection between frictionallyengaging said segment lever beyond the point of attachment to saidsegment lever for dampening the motion of said resilient link.

LEON DEW AN.

